To Study Ancient Humans, Archeologists Are Using… What?!


[♪ INTRO] When you think about archeologists, you might imagine people who spend years in the dirt, digging around to learn about old cultures and civilizations. But while field work is important, there’s also a lot more going on these days. In fact, in the last few years, archeologists have even started borrowing and adapting methods from other fields to advance their
own work. So today, while you will find some researchers knee-deep in dust, you’ll find others using
techniques from computer science, meteorology, and even astronomy to learn about people who used to walk the Earth. First, satellites. These things are often associated with militaries and tech companies, but recently, they’ve
been used to help archaeologists, too. Satellites might not spot ancient bones or pottery, but they can see a whole region at once. That lets us find larger patterns and big-picture details we can’t pick up from the ground. And by studying areas using different kinds of light, satellites can also reveal hidden
structures. For example, in 2011, the BBC announced that researchers studying Egypt had used infrared satellite images to spot mud walls underneath
the sand. According to those researchers, the walls absorbed water, so they looked different in infrared than the drier sand over them. Further analysis of these images revealed that there could be previously unknown cities down there, too — including thousands of buried homes and buildings, and possibly a dozen or so new pyramids. If they exist, these sites are likely around three or four thousand years old, and they could teach us more about how your average Egyptian lived backed them. Also: New pyramids! Outside of Egypt, satellites have also helped
us discover Viking settlements in Canada and map sites throughout Peru. They’ve even shown traces left by those who stole from archaeological sites. Which is less fun, but is a major problem in the field and something to keep track of. Satellites can only do so much, though, because you don’t always have a clear view of the ground. For example, places like Peru, Guatemala, Belize, and even New England have pretty dense forests that satellites can’t see through. They’re also hard for archeologists to reach in person. So lately, scientists have started mapping beneath the canopy with a method used in everything from meteorology to self-driving
cars. It’s called LiDAR, which is short for Light Detection and Ranging. In this method, they fly a plane overhead and point a laser at the ground. Then, some of that laser light sneaks through the leaves and gets reflected by whatever is down there. By measuring how long it takes for the light to return to the plane, scientists can calculate the distance to the canopy, the ground, and whatever structures might be hidden on the forest floor. That gives them a complete 3-D map of the area. In the last decade, LiDAR has revealed ancient Spanish gold mines, sunken Roman villas, and in 2018, a huge, densely-populated network of Maya settlements in Guatemala. The settlements involve hundreds of square kilometers of cities, towns, roads
— and over a thousand years ago, more than ten million people likely lived
there! And we found it all without a single archaeologist coming face-to-face with a jaguar. If you think about it, satellites and LiDAR feel like pretty intuitive technologies for archeologists to adopt. But this last method is a lot stranger because it takes a page out of astronomers’
playbooks. It involves some of the most powerful things in the universe: supernovas. These are huge explosions some stars undergo at the end of their lives, and they’re one source of high-energy particles called cosmic rays. These rays aren’t harmful to us on the ground, but researchers pay a lot of attention to
them for other reasons: Physicists, for example, use them to understand the subatomic realm. But in 2017, cosmic rays revealed something new in archeology, when physicists used them to discover a huge new room inside the Great Pyramid at Giza. They went inside the pyramid and used detectors to measure how many cosmic rays there were in various spots. Specifically, they were looking for one type of particle called muons. The idea was that fewer muons can get through something dense — like enormous sandstone
blocks. So if they saw an area with more muons than normal, that would suggest there was a room somewhere above them. And that’s what they saw. They noticed more muons than expected coming from just above the Grand Gallery — the largest room in the pyramid. And after doing some follow-up tests, they concluded that there was a huge, completely unexpected room up there. No one is quite sure why it exists, but this was still significant, considering that the Great Pyramid is one of the most famous archaeological sites in the world. It was the first new room anyone had discovered there in more than a century, and the researchers found it without breaking any ancient walls. Scientists are currently on the lookout for more places to turn their cosmic ray detectors. But finding a new room inside one of the Seven Wonders of the World is impressive enough for now. And it’s just one more way that archaeology is changing and embracing new technologies. Never fear, though: The field still hasn’t lost its roots. After all, when something like a satellite reveals an ancient city, someone still has to go explore it in person. Thanks for watching this episode of SciShow, and thanks to all of our patrons for making
it happen! You help us keep the lights on, develop sweet graphics, and make sure our content is accurate. So we really can’t say thank-you enough. If you want to learn how to support free science content on the Internet, you can head over to patreon.com/scishow. [♪ OUTRO]